1. Field of the Invention
The present invention relates to an information display system including a main unit for generating display data and a head-mounted unit for displaying information.
2. Description of the Related Art
Display apparatuses for observing images by wearing on a head, such as a HMD (head-mounted display) and a HUD (head up display), have been known.
As an example of such a display apparatus, a head-mounted display system is disclosed in Japanese Unexamined Patent Application Publication No. 10-123970, in which a display portion for use by wearing on a head and a control unit having a battery for supplying electric power to the entire system and controlling the display portion are connected together via cables.
As another example, Japanese Unexamined Patent Application Publication No. 2001-8130 also discloses an apparatus that includes a head-mounted image display apparatus for observing images in a state mounted on a head and a DVD player connected to the head-mounted image display apparatus via cables for feeding an image signal to the display apparatus. In this Publication, a technique is also described in which when an image signal to be inputted to the head-mounted image display apparatus does not exist, useless electric power consumption is suppressed by stopping the power supply to the head-mounted image display apparatus.
In such a manner, in these Publications, described is a display apparatus in which a display portion to be mounted on a head and a control unit configured independently from the display portion for controlling the display portion are connected via cables and a battery attached on the display portion supplies power to the entire system including both units.
However, in the systems described in both the Publications, in addition to cables for sending image signals, cables for supplying electric power are necessary, so that cables are increased in diameter. If the cables have a large diameter, they are somewhat difficult to be curved and routed around while the weight of the cables is applied to the display portion to be mounted on a head, so that an observer feels the weight of the display portion heavier than its actual weight. Moreover, when cables are used for connecting the display portion to the control unit, cables may be coiled around the observer's body when used, and when the system is carried in a bag, cables may get entangled with themselves, the control unit, or the display portion, so that the system is not so user-friendly.
Furthermore, in the systems described in both the Publications, when the head-mounted unit is not in service, if the power supply is turned on by mistake, the electric power is consumed in vain.